Today, radio communication networks typically comprise radio base stations with associated cells that are continuously active. This means that the radio base stations more or less continuously transmit certain forms of signals in the cells to assist user equipment present in the radio communication network or user equipment attempting to connect thereto. Examples of such signals are pilot signals, such as reference and synchronization signals, and the broadcast channel. These signals are used for many purposes including downlink (DL) channel estimation, cell synchronization in connection with power-up of user equipment and mobility cell search.
In Wideband Code Division Multiple Access (WCDMA) a NodeB for a cell can be put to sleep at night by switching off the power supply to the NodeB in order to reduce power consumption. In the morning, the NodeB is turned on again by once more providing power supply to the NodeB.